Metallocene catalysts have high activities and are capable of preparing resin with enhanced physical properties in comparison with the resin polymerized by using Ziegler-Natta catalysts. The metallocene catalysts are compounds of Group IV transition metals of the Periodic Table such as titanium, zirconium, hafnium, etc., and have a coordinated structure with a metal compound and ligands composed of one or two groups of cyclopentadienyl, indenyl, fluorenyl or their derivatives. The metallocene catalysts are usually employed with a co-catalyst. And the co-catalyst is normally an alkylaluminoxane such as methylaluminoxane prepared by reacting an alkylaluminium compound with H.sub.2 O, unlike the co-catalyst employed with the Ziegler-Natta catalysts.
U.S. Pat. No. 3,740,384 discloses a process for polymerization of mono-olefins by contacting the olefin with a catalyst composition containing an organomettallic zirconium complex selected from hydrocarbyl complexes of zirconium in which the valence or co-ordination requirements of the metal are satisfied by alkyl, alkenyl, or arylalkyl groups which may be partially replaced by other monovalent ligands, using the catalyst composition of 1,1,3,3-tetraphenylsiloxane-1,3-diol. The organometallic zirconium compounds contain allyl, ethylbenzyl, methylene or naphthyl ligands.
EP Publication No. 423 872 A2 discloses a reaction product (for example, Cp.sub.2 ZrR.sub.2, R=alkyl or halogen) of a silicon of siloxane diol and a dicyclopentadienyl zirconium as a catalyst for ethylene polymerization.
The inventors of the present invention have discovered that the metallocene catalyst prepared by reacting a diol (or diamine, alkyl dimagnesium halide, aryl dimagnesium halide) compound with a cyclopentadienyl zirconium halide has a higher activity in preparation of olefin polymers than conventional catalysts, and that the metallocene catalysts are capable of using less amount of a co-catalyst such as an alkylaluminoxane than conventional catalysts when they are employed in preparation of olefin polymers.
Accordingly, the present inventors have developed new metallocene catalysts for use in preparation of olefin polymers, and methods of preparing the metallocene catalysts and methods of preparing olefin polymers such as mono-polymers of ethylene or .alpha.-olefin, ethylene/.alpha.-olefin co-polymers, propylene/.alpha.-olefin co-polymers, etc using the metallocene catalysts.